title: Multilocus sequence typing analysis of Clostridium perfringens isolates from necrotic enteritis outbreaks in broiler chicken populations.
abstract: Clostridium perfringens is an important pathogen of animals and humans and is the causative agent of necrotic enteritis (NE) in poultry. This study focuses on the typing of intestinal C. perfringens isolates (n = 61) from outbreaks of NE collected from several areas of Southern Ontario, using a recently developed multilocus sequence typing (MLST) technique. For comparison, C. perfringens isolates from healthy birds were also obtained and typed. An additional locus, the pfoS locus, was included in our analysis, in an attempt to increase the discriminatory ability of the method previously published. Birds were collected from two major poultry processors in Canada, and isolates from processor 2 formed a distinct MLST cluster. Isolates from healthy birds also collected from the outbreak flocks clustered together with isolates from the birds with NE. Although isolates from eight outbreaks clustered together, MLST types were also occasionally different between outbreaks. Strong linkage disequilibrium was observed between loci, suggesting a clonal C. perfringens population structure. Detection assays for toxin genes cpb2 (beta-2 toxin), tpeL, and the newly described netB (NetB toxin) were also performed. netB was almost always found in outbreak isolates, whereas cpb2 was found exclusively in healthy bird isolates. The toxin gene tpeL, which has not been previously identified in C. perfringens type A strains, was also found, but only in the presence of netB. Resistance to bacitracin was found in 34% of isolates from antimicrobial agent-free birds and in 100% of isolates from conventionally raised birds.
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Chalmers
authors.forename: H L
authors.initials: HL
authors.lastname: Bruce
authors.forename: D B
authors.initials: DB
authors.lastname: Hunter
authors.forename: V R
authors.initials: VR
authors.lastname: Parreira
authors.forename: R R
authors.initials: RR
authors.lastname: Kulkarni
authors.forename: Y-F
authors.initials: YF
authors.lastname: Jiang
authors.forename: J F
authors.initials: JF
authors.lastname: Prescott
authors.forename: P
authors.initials: P
authors.lastname: Boerlin
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001414:Bacitracin / Q000494:pharmacology; D001427:Bacterial Toxins / Q000235:genetics; D015373:Bacterial Typing Techniques / Q000379:methods*; D001717:Birds; D002645:Chickens; D003015:Clostridium Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D003016:Clostridium perfringens / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D016000:Cluster Analysis; D016172:DNA Fingerprinting / Q000379:methods; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial; D004751:Enteritis / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005838:Genotype; D009864:Ontario / Q000453:epidemiology; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004269:DNA, Bacterial; D037521:Virulence Factors; D001414:Bacitracin